Mobile systems with seamless transition by activating second subsystem to continue operation of application executed by first subsystem as it enters sleep mode

ABSTRACT

A computer system includes two or more subsystems. In one example, a first subsystem is executing a multimedia application using data stored in a first storage device. A copy of the data is also stored in a second storage device associated with a second subsystem. The second subsystem may be a dedicated multimedia player controller. When the first subsystem is to enter a sleep state, the second subsystem may continue to process the multimedia data stored in the second storage device. The second subsystem may also use the same audio port that the first subsystem was using before it enters the sleep state. Appropriate transition point may be determined by the second subsystem to ease audio disruption.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is related and claims priority to U.S. patentapplication Ser. No. 14/288,160 titled “MOBILE SYSTEMS WITH SEAMLESSTRANSITION BY ACTIVATING SECOND SUBSYSTEM TO CONTINUE OPERATION OFAPPLICATION EXECUTED BY FIRST SUBSYSTEM AS IT ENTERS INTO SLEEP MODE”filed May 27, 2014; which claims priority to U.S. patent applicationSer. No. 12/380,736 titled, “MOBILE SYSTEMS WITH SEAMLESS TRANSITION BYACTIVATING SECOND SUBSYSTEM TO CONTINUE OPERATION OF APPLICATIONEXECUTED BY FIRST SUBSYSTEM AS IT ENTERS INTO SLEEP MODE” filed Mar. 3,2009, and is now granted U.S. Pat. No. 8,738,951; which claims priorityto U.S. patent application Ser. No. 11/127,909 titled, “MOBILE SYSTEMSWITH SEAMLESS TRANSITION BY ACTIVATING SECOND SUBSYSTEM TO CONTINUEOPERATION OF APPLICATION EXECUTED BY FIRST SUBSYSTEM AS IT ENTERS INTOSLEEP MODE” filed May 11, 2005, and is now granted U.S. Pat. No.7,500,128. This application is entirely incorporated by reference.

FIELD OF INVENTION

The present invention relates generally to the field of powermanagement. More specifically, the present invention relates toproviding seamless transition of among different operating environments.

BACKGROUND

Portable computer systems are becoming increasingly popular. Power to aportable computer system is normally provided by a direct current (DC)power source such as, for example, a battery. One concern with the useof the battery is the battery life. Depending on how the computer systemis used, the frequency of how often the battery may need to be rechargedmay vary. As more advanced applications are developed, the balancebetween the user experience and the battery life becomes more evident. Acomputer system operating in a high power consumption mode may providean excellent user experience, but it may drain the battery faster thanwhen the computer system is operating in a low power consumption mode.When the battery is drained, an application may end abruptly and thuscan negatively affect the user experience. Efforts are being developedto improve the user experience while reducing the effect of the batterylife.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention may be best understood by referring to the followingdescription and accompanying drawings that are used to illustrateembodiments of the invention. In the drawings:

FIG. 1A illustrates an example of a computer system, in accordance withone embodiment.

FIG. 1B illustrates an example of different states of a processor in acomputer system, in accordance with one embodiment.

FIG. 2 illustrates an example of a computer system having twosubsystems, in accordance with one embodiment.

FIG. 3A illustrates an example of a hardware architecture for a computersystem having an MP3 subsystem, in accordance with one embodiment.

FIG. 3B illustrates an example of a software architecture for a computersystem having an MP3 subsystem, in accordance with one embodiment.

FIG. 4A illustrates an example of a computer system having multiplesubsystems, in accordance with one embodiment.

FIG. 4B illustrates an example of a computer system having multiplesubsystems in low power states, in accordance with one embodiment.

FIG. 5 illustrates an example of a computer system having a detachablesubsystem, in accordance with one embodiment.

FIG. 6 illustrates an example of a process used to transition betweentwo operating environments, in accordance with one embodiment.

DESCRIPTION

In some embodiments, a computer system may include two or moresubsystems. The two or more subsystems may share a data bus and mayprocess related data at different times. When a first subsystem goesinto a low power state, a transition to a second subsystem may occur.The second subsystem may continue to process the data that was beingprocessed by the first subsystem prior to the first subsystem going intothe low power state. The processing of the data by the second subsystemmay include identifying a transition point in the data to reduce anydisruption caused by the second subsystem continuing to process thedata.

In the following description, for purposes of explanation, numerousspecific details are set forth to provide a thorough understanding ofthe present invention. It will be evident, however, to one skilled inthe art that the present invention may be practiced without thesespecific details. In other instances, well known structures, processes,and devices are shown in block diagram form or are referred to in asummary manner in order to provide an explanation without undue detail.

Computer System

FIG. 1A is a block diagram illustrating an example of a computer systemthat may be used, in accordance with an embodiment of the invention.Computer system 100 may include a central processing unit (CPU) 102 andmay receive its power from an electrical outlet or a battery (notshown). The CPU 102 and chipset 107 may be coupled to bus 105.

The chipset 107 may include a memory control hub (MCH) 110. The MCH 110may include a memory controller 112 that is coupled to memory 115. Thememory 115 may store data and sequences of instructions that areexecuted by the CPU 102 or any other processing devices included in thecomputer system 100. The data may include time dependent or isochronousdata that needs to be processed or delivered within certain timeconstraints. For example, multimedia streams require an isochronoustransport mechanism to ensure that data is delivered as fast as it isdisplayed and to ensure that the audio is synchronized with the video.The data may include asynchronous data which may be delivered in randomintervals, and synchronous data which may be delivered only at specificintervals.

The MCH 110 may include a graphics interface 113. Display 130 may becoupled to the graphics interface 113. The chipset 107 may also includean input/output control hub (ICH) 140. The ICH 140 is coupled with theMCH 110 via a hub interface. The ICH 140 provides an interface toinput/output (I/O) devices within the computer system 100. The ICH 140may include PCI bridge 146 that provides an interface to PCI bus 142.The PCI bridge 146 may provide a data path between the CPU 102 andperipheral devices. An audio device 150 and a disk drive 155 may beconnected to the PCI bus 142. The disk drive 155 may include a storagemedia to store data and sequences of instructions that are executed bythe CPU 102 or any other processing devices included in the computersystem 100. Although not shown, other devices (e.g., keyboard, mouse,etc.) may also be connected to the PCI bus 142 or other system bus.

FIG. 1B illustrates an example of a state diagram for a computer system.Examples of the operating states illustrated in FIG. 1B may be found inthe Advanced Configuration and Power Interface (ACPI) Specification,Revision 2.0a dated Mar. 31, 2002 (and published by Compaq ComputerCorporation, Intel Corporation, Microsoft Corporation, PhoenixTechnologies Ltd., and Toshiba Corporation). Referring to FIG. 1B, afirst state 180 (referred to as “normal on” state) is the normaloperating state of the computer system 100. Within the ACPIspecification, the “normal on” state 180 is referred to as the “G0”state. A second state 170 refers to any one or more states where thecomputer system 100 is recognized as being “off”. The ACPI specificationrecognizes two such off states: a hardware based off state (e.g., wherepower has been removed from the entire system) and a software based offstate (where power is provided to the system but the BIOS and operatingsystem (OS) have to be reloaded from scratch without reference to thestored context of a previously operating environment). The ACPIspecification refers to the hardware based off state as the “G3” stateand the software based off state as the “G2” state.

A third state 190 refers to any of one or more states where the computersystem 100 is recognized as “sleep”. For sleep states, the operatingenvironment (also referred to as a context) of the computer system 100in the “normal on” state 180 is saved prior to the CPU 102 of thecomputer system 100 being entered into a low power consumption state.The sleep state(s) 190 are aimed at saving power consumed by the CPU 102over a lull period in the continuous use of the computer system 100. Thesaved operating environment is restored as part of the transition backto the “normal on” state 180 from the sleep state(s) 190. The ACPIspecification recognizes a collection of different sleep states (notablythe “S1”, “S2”, “S3” and “S4” states) each having its own respectivebalance between power savings and delay or latency when returning to the“normal on” state 180 (here, the S1, S2 and S3 states are recognized asbeing various flavors of “standby” and the S4 state is a “hibernate”state). Although power consumed by the CPU 102 is reduced when it is inone of the sleep state 190, the CPU 102 may not be able to perform work.Although the ACPI specification is recognized as describing a largenumber of existing computer systems, it should be recognized that largenumbers of computer systems may not conform to the ACPI specificationbut still conform to the operating state configuration observed in FIG.1B. As such, the description of FIG. 1A may correspond to a more genericcomputer system that may or may not conform to the ACPI specification.

Multiple Subsystems

FIG. 2 illustrates an example of a computer system having twosubsystems, in accordance with one embodiment. In this example, computersystem 200 may include two subsystems 201 and 202. The subsystem 201 mayinclude CPU 205, and subsystem 202 may include CPU 210. Although notshown, each of the subsystems 201 and 202 may also include other devicessuch as, for example, memory, I/O devices, etc. The subsystems 201 and202 may both be active at the same time, or one subsystem may be activewhile the other is not. For example, both the subsystems 201 and 202 maybe in the “normal on” state 180. As another example, the subsystem 201may be in a sleep state 190 while the subsystem 202 may be in the“normal on” state 180. Other operating state combinations may also bepossible.

For one embodiment, the subsystems 201 and 202 may share some commonbus. The common bus may include a data bus, an instruction bus, a signalline, etc. The subsystems 201 and 202 may also have access to commondevices. For example, the subsystems 202 may be able to access a storagedevice or an input/output device associated with the subsystem 210.

For one embodiment, the subsystems 201 and 202 may be tightly coupled.For example, the computer system 200 may be a laptop computer systemhaving a lid unit and a base unit, and the CPU 205 in the subsystem 201may be a main processor and the CPU 210 in the subsystem 202 may be anon-main processor. The CPU 205 may be coupled to the display 130serving as a primary display. The CPU 210 may be coupled to a smallersecondary display (not shown). The secondary display may be located onthe exterior side of the lid unit and may be used to display informationsimilar to, for example, Personal Information Management (PIM)information or information typically displayed by a Personal DigitalAssistant (PDA).

For another embodiment, the subsystems 201 and 202 may be looselycoupled. That is, in addition to operating together with the subsystem201 when coupled, the subsystem 202 may be separated from the subsystem201 and may operate independently of the subsystem 201 as two separatesystems. Of course, the subsystem 202 may later be re-coupled to thesubsystem 201.

Depending on the application(s) being executed and/or the type of databeing delivered by either or both of the subsystems 201 and 202, theremay be synchronization issue. For example, while processing a datastream, the subsystem 201 may enter the sleep state 190. The subsystem202 may remain in the “normal on” state 180 and may continue to processthe same data stream after certain transition latency. The effect of thetransition latency may be significant (e.g., audio disruption, videodistortion, etc.) and may affect user experience. Although the currentexample refers to two subsystems, the computer system 200 may includemore than two subsystems.

FIG. 3A illustrates an example of hardware architecture for a computersystem having multiple subsystems, in accordance with one embodiment. Inthis example, computer system 300 may be a laptop computer system havinga lid unit and a base unit (not shown) in a clamshell form factor. Thereare two subsystems 301 and 302, and they may operate independently ofone another or they may work together (e.g., in serial or in parallel)processing the same data stream.

A battery 303 may be used to provide power to the subsystem 301. Thesubsystem 301 includes CPU 308, graphics and memory controller hub(GMCH) 310 and I/O controller hub (ICH) 315. The CPU 308 may be viewedas a main processor. The GMCH 310 is coupled to display (or primarydisplay) 304. The ICH 315 is coupled to a coder/decoder (CODEC) 335which is coupled to audio output logic. The audio out logic may includean amplifier 340 and output signals for a line out and a speaker.

Data may be stored in a storage device or hard disk drive (HDD) 330.Data may also be provided externally using various memory devices (e.g.,compact flash card, smart media card, multimedia card, secure digitalcard, memory stick card, microdrive, etc.) via a memory reader 320coupled to the ICH 315. In this example, the data may include audioand/or video data. For example, the audio data may be encoded in MP3format and stored in the HDD 330. The CPU 308 may execute an MP3 playerapplication (e.g., Musicmatch Jukebox from Musicmatch of San Diego,Calif.) which retrieves the MP3 encoded data from the HDD 330 anddeliver it to the amplifier 340 via the CODEC 335. Furthermore, the CPU308 may execute a DVD player application (e.g., directDVD fromOrionStudios of Los Angeles, Calif.) that delivers audio data and videodata from the HDD 330 to the amplifier 340 and to the display 304,respectively.

The subsystem 302 may be a multimedia player subsystem. Power to thesubsystem 302 may also be provided by the battery 303 via voltageregulator (VR) 306. Although not shown, the subsystem 302 may alsoinclude its own power source. The subsystem 302 may include its owndisplay (or secondary display) 355 and local memory (e.g., flash) 360.Different techniques (e.g., switches, software push buttons, etc.) maybe used to control various operations of the subsystem 302. Theseoperations may include, for example, power on/off, fast forward, rewind,pause, etc.

In this example, the subsystem 302 may include an MP3 player controller350 (e.g., MP3 player controller from Integrated Circuit Solution Inc.(ICSI) of Taiwan) which may be viewed as a non-main processor. Thesubsystem 302 may also include its own MP3 decoder (not shown) and maybe able to access data from external memory devices (e.g., smart media,etc.). In this example, it is envisioned that the power consumptionassociated with the subsystem 302 is low compare to that of thesubsystem 301.

For one embodiment, the subsystem 302 may share some devices associatedwith the subsystem 301. These shared devices may include input andoutput devices. For example, the subsystem 302 may include a serial databus 311 connected to a multiplexer (MUX) 325 to enable the subsystem 302to access the HDD 330 and possibly other I/O devices connected to theICH 315. For one embodiment, the subsystem 302 may include an audio outsignal 370 that may be connected to the audio output logic and amplifier340 of the subsystem 301. For another embodiment, the local memory 360may include a subset of the data stored in the HDD 330 or in theexternal memory coupled the memory reader 320. For example, the localmemory 360 may contain at least a copy of an MP3 play list that is beingprocessed by the subsystem 301. For one embodiment, the data in thelocal memory 360 may be updated periodically based on the data beingprocessed by the subsystem 301. Other communications between thesubsystem 301 and the subsystem 302 may be carried out using the systemmanagement bus (SMB) 313.

When the lid unit of the computer system 300 is closed onto the baseunit, the subsystem 301 may transition from a “normal on” state 180 tothe sleep state 190. The subsystem 302 may remain in the “normal on”state 180. For one embodiment, a lid closed signal 307 may be generatedand sent from the subsystem 301 to the subsystem 302. The subsystem 301may stop processing the data, but the subsystem 302 may take over andcontinue to process the same data. The ICH 315 may include edgetransition logic to detect the state transition of the lid closed signal307. For example, when the lid unit is opened, the state of the lidclosed signal 307 may be “0”. When the lid unit is closed, the state ofthe lid closed signal 307 may be “1”. For one embodiment, the edgetransition logic may remain powered on even when the subsystem 301 is ina sleep state.

Depending on the capacity of the local memory 360, the subsystem 302 mayor may not need to communicate with the subsystem 301. For oneembodiment, when additional data is needed, the subsystem 302 may wakeup the subsystem 301 using the wake signal 312. For example, when thesubsystem 302 almost completes processing an MP3 play list, thesubsystem 302 may use the wake signal 312 to wake up the subsystem 301to download additional play lists from the HDD 330. The download processdata may be performed using the serial bus 311, and the additional playlists may be stored in the local memory 360. For one embodiment, whenthe download process is completed, the subsystem 301 may return to thesleep state.

When the lid unit is opened, the subsystem 302 may transition theprocessing of the data to the subsystem 301. It may be noted thatbecause the audio data from the subsystem 302 is multiplexed to theaudio output logic of the subsystem 301, the audio data may continue tobe delivered by the subsystem 301 (e.g., via the HDD 330) to the audiooutput logic with little disruption. Similarly, the video data may bedirected from the secondary display 355 to the primary display 304.Alternatively, the video data may be multiplexed to both the primarydisplay 304 and the secondary display 355.

FIG. 3B illustrates an example of process that may be used to transitionbetween subsystems, in accordance with one embodiment. The process maybe used in a computer system having two subsystems, with one subsystemincluding an MP3 player controller. The process may start at block 371where a first subsystem is processing data. At block 372, a test isperformed to determine if the first subsystem is exiting the “normal on”state and entering the sleep state. If the first subsystem is notexiting the “normal on” state, the process continues at block 373 wherethe first system continues to process the data.

If the first subsystem is exiting the “normal on” state, the processcontinues to block 374. At block 374, a test is performed to determineif the second subsystem is activated. It may be possible that when thefirst subsystem is in the “normal on” state, the second subsystem isalso in the “normal on” state, and when the first system exits the“normal on” state, the second subsystem remains in the “normal on”state. Alternatively, when the first subsystem exits the “normal on”state, the second subsystem may need to be activated to be or to remainin the “normal on” state; otherwise, it may also exit the “normal on”state.

From block 374, if the second subsystem is not in the “normal on” state,the process may end at block 386. Otherwise, the process may continue atblock 376. For one embodiment, the second subsystem may identify anappropriate transition point in the data to take over the processing ofthe data from the first subsystem. For example, when the data is audiodata, the transition point may be a within a silent duration. When thedata is MP3 data, the transition point may be between songs so that thesecond subsystem may fad in. The second subsystem may also perform someaudio effects to ease the transition process and to reduce audiodisruption. When the data is video data, the transition point may bewhen there is a scene change. A transition point may be introduced bypresenting some video effects in the process to reduce video disruption.

At block 377, the second subsystem processes the data in the localmemory. As mentioned above, the data in the local memory may be a subsetof the data that is stored in the first subsystem. The data in the localmemory may be limited and the second subsystem may exhaust the databefore the first subsystem exits the sleep state. For example, when thesecond subsystem is de-coupled from the first subsystem, the secondsubsystem may exhaust the data in its local memory before the secondsubsystem is re-coupled to the first subsystem. In this example, thefirst subsystem may automatically exit the sleep state when the secondsubsystem is re-coupled. Alternatively, the first subsystem may need tobe awakened to exit the sleep state even when the second subsystem isre-coupled to it.

At block 380, a test is performed to determine if the first system exitsthe sleep state and enters the “normal on” state. If it does not exitthe sleep state, the process continues at block 377. If it exits thesleep state, the process continues at block 382, where the firstsubsystem identifies a transition point to take over the processing ofthe data from the second subsystem. At block 382, the first subsystemaccesses and processes the data from its own storage device. The processthen continues at block 384, then 373.

Although some of the above examples refer to computer systems having twosubsystems, it is possible that a computer system may have more than twosubsystems. For example, illustrated in FIG. 4A, computer system 400includes four subsystems 405-420. One or more of the subsystems 411, 416and 421 may be detached from the computer system 400, and one or more ofthese subsystems may be remain in the “normal on” state when thesubsystem 405 enters the sleep state. This is illustrated in the examplein FIG. 4B where the subsystems 405, 415, 420 are in the sleep statewhile the subsystem 410 is in the “normal on” state.

FIG. 5 illustrates an example of a computer system having a detachablesubsystem, in accordance with one embodiment. Computer system 500 issimilar to the computer system 400 illustrated in FIG. 4B. In thisexample, the subsystem 410 may be detached from the computer system 500and may remain in the “normal on” state when the other subsystem(s) inthe computer system 500 may be in the sleep state. It may be noted thatthe subsystem 410 may share some I/O devices with the subsystems 405when the subsystem 410 is attached to the computer system 500. Althoughthe subsystem 410 may have its own I/O devices, the sharing of I/Odevices with the subsystem 405 may be possible using wirelesscommunication (e.g., Bluetooth, etc.) when the subsystem 405 is detachedfrom the computer system 500. In the current example, the subsystem 505may operate with its own power supply and I/O devices including itsstorage device, display, speakers, etc.

As an example, the computer system 500 may be a multimedia computersystem performing operations as provided by a media center. The computersystem 500 may receive input (e.g., TV programs, movies, news, etc.)from various data sources via an Internet connection, a cable modem, asatellite connection, etc. The computer system 500 may be coupled to aprogram recording logic such as, for example, a TiVo system from TiVoInc. of Alviso, Calif. The computer system 500 may be operating with theWindows XP operating system from Microsoft Corporation of Redmond, Wash.The computer system 500 may also execute media center software such as,for example, Media Center for Windows XP from Microsoft.

The subsystem 405 may be a TiVo system and may play a recorded videoprogram stored on its storage device. The video program may be displayedon a display or on a television screen connected to a video output portassociated with the subsystem 405.

The subsystem 410 may be capable of operating independently of thesubsystem 405. For example, the subsystem 410 may be a small form factorentertainment subsystem that may be attached to or detached from thecomputer system 500 via a docking station (not shown).

A copy of the data stored in the subsystem 405 may be stored in thesubsystem 410. For example, a video program may be downloaded to thestorage device of the subsystem 405 from a video supplier or a networkfeed while the subsystem 410 is in the sleep state. The subsystem 405may wake up the subsystem 410, and the video program may be copied andstored in the local memory or storage device of the subsystem 410. Thesubsystem 410 may then re-enter the sleep state.

It may be possible that the copying of the data or video program in theabove example may be initiated by the subsystem 410. For example, whenthe subsystem 405 is in the sleep state, the subsystem 410 may need towake up the subsystem 405. This may be performed via a wake up signalwhen the subsystem 410 is coupled to the subsystem 405, or it may beperformed via a wireless communication signal when the subsystem 410 ispositioned near the subsystem 405. When the data is copied to thesubsystem 410, the subsystem 405 may re-enter the sleep state.

When a user who is viewing the video program on the television screen(connected to the TiVo subsystem) needs to move to a different location,the user may detach the subsystem 410 from the computer system 500.Because the subsystem 410 has a copy of the video program, the user maycontinue to view the video program on the display associated with thesubsystem 410.

There may be some synchronizing process that enables the subsystem 410to continue the video program at the appropriate position. For oneembodiment, the synchronizing process may include the subsystem 405sending synchronizing information associated with the data beingprocessed to the subsystem 410. For example, the subsystem 405 may sendpacket identification number (PID), time stamp, or chronologicalinformation to the subsystem 410 to enable the subsystem 410 tosynchronize with the data stored in its local memory and to pickup theprocessing of the data at the appropriate position. This may enable theuser to continue to watch the video program using the subsystem 410. Asdescribed above, some audio and/or video effects may be used to helpwith the transition.

When the subsystem 410 is re-coupled to the subsystem 405, the subsystem410 may also send synchronizing information to the subsystem 405. Forexample, the subsystem 405 may request the subsystem 410 to send thesynchronizing information. This may enable the subsystem 405 to takeover the processing of the data when the subsystem 405 exits the sleepstate. For one embodiment, the synchronizing information may beexchanged between the subsystem 405 and the subsystem 410 when the lidclosed signal 307 and the wake signal 312 (as illustrated in FIG. 3A)are sent.

It may be possible that the subsystem 405 enters the sleep state afterthe subsystem 410 is detached. Alternatively, the subsystem 405 mayremain in its “normal on” state and may continue to play the videoprogram independent of the subsystem 410, as illustrated in FIG. 6. Itmay be possible that the subsystem 405 may proceed to play a differentvideo or audio program from the program being played by the subsystem410.

Computer Readable Media

In some embodiments, it is also to be understood that they may beimplemented as one or more software programs stored within a machinereadable medium. A machine readable medium includes any mechanism forstoring or transmitting information in a form readable by a machine(e.g., a computer). For example, a machine readable medium includes readonly memory (ROM); random access memory (RAM); magnetic disk storagemedia; optical storage media; flash memory devices; electrical, optical,acoustical or other form of propagated signals (e.g., carrier waves,infrared signals, digital signals, etc.); etc.

In the foregoing specification, the invention has been described withreference to specific exemplary embodiments thereof. It will, however,be evident that various modifications and changes may be made theretowithout departing from the broader spirit and scope of the invention asset forth in the appended claims. The specification and drawings are,accordingly, to be regarded in an illustrative rather than a restrictivesense.

What is claimed is:
 1. A first system comprising: first memory; a firstoutput device; and a communication interface, wherein the first systemis communicatively coupled, via the communication interface, to a secondsystem comprising (i) second memory storing first data, and (ii) asecond output device, wherein the first system is configured to: whilethe second system is in a first mode, wherein the first mode is a normaloperation mode, (i) receive, from the second system, a first subset ofthe first data from the second memory, (ii) output, via the first outputdevice, the first subset of the first data received from the secondsystem, (iii) store, in the first memory, a second subset of the firstdata from the second memory, and (iv) synchronize data stored in atleast a part of the first memory with data stored in at least a part ofthe second memory via synchronization information, wherein thesynchronization information is to include a packet identificationnumber, a time stamp, or chronological information, and while the secondsystem is in a second mode, wherein the second mode is a low poweroperation mode, (i) refrain from accessing the second memory, and (ii)output, via the first output device, the second subset of the first datafrom the first memory.
 2. The first system of claim 1, wherein secondsystem is inaccessible during the second mode.
 3. The first system ofclaim 1, wherein: the first mode is a normal operation mode in which afirst amount of power is consumed; and a power consumed during thesecond mode is less than the first amount of power.
 4. The first systemof claim 1, wherein the first output device comprises an audio outputdevice.
 5. The first system of claim 1, wherein the first output devicecomprises a display.
 6. The first system of claim 1, wherein the secondoutput device comprises a display.
 7. The first system of claim 1,wherein the first system is further configured to: in response to thesecond system transitioning from the second mode to the first mode,access the second memory to receive a third subset of the first datafrom the second memory; and store the third subset of the first data inthe first memory, for outputting the third subset of the first data at asubsequent time via the first output device.
 8. A first apparatus,comprising: a first display; a first storage device; and a first outputdevice, wherein the first apparatus is configured to be selectivelycoupled to a second apparatus comprising a second storage device and asecond output device, and wherein the first apparatus is configured to:while the second apparatus is in a first mode, wherein the first mode isa normal operation mode, and is communicatively accessible by the firstapparatus, (i) receive, from the second apparatus, first data based onthe second system executing a first application, (ii) output, via thefirst output device, the first data, (iii) receive second data from thesecond storage device, (iv) store the second data in the first storagedevice, and (v) synchronize data stored in at least a part of the firststorage device with data stored in at least a part of the second storagedevice via synchronization information, wherein the synchronizationinformation is to include a packet identification number, a time stamp,or chronological information, and while the second apparatus is in asecond mode, wherein the second mode is a low power operation mode, andis communicatively inaccessible to the first apparatus, (i) execute asecond application, and (ii) in response to executing the secondapplication, output, via the first output device, the second data fromthe first storage device.
 9. The first apparatus of claim 8, wherein thefirst output device comprises an audio output device.
 10. One or morenon-transitory computer-readable storage medium configured to storeinstructions that, when executed by a processor of a first system, causethe processor to: determine a mode of operation of a second system,wherein the first system comprises first memory and a first outputdevice, and wherein the second system comprises second memory and asecond output device; while the second system is in a first mode,wherein the first mode is a normal operation mode, receive, from thesecond system, a first subset of the first data from the second memory;while the second system is in the first mode, output, via the firstoutput device, the first subset of the first data received from thesecond system; while the second system is in the first mode, store, inthe first memory, a second subset of the first data from the secondmemory; while the second system is in the first mode, synchronize datastored in at least a part of the first memory with data stored in atleast a part of the second memory via synchronization information,wherein the synchronization information is to include a packetidentification number, a time stamp, or chronological information; andwhile the second system is in a second mode, wherein the second mode isa low power operation mode, output, via the first output device, thesecond subset of the first data from the first memory.
 11. The one ormore non-transitory computer-readable storage medium of claim 10,wherein the second mode is a low power operation mode during which thesecond system is un-accessible to the first system.
 12. The one or morenon-transitory computer-readable storage medium of claim 10, wherein theinstructions, when executed, further cause the processor to: receive,from the second system, the first subset of the first data from thesecond memory based on the second system executing a first application;and output, via the first output device, the second subset of the firstdata from the first memory based on the second system executing a secondapplication.
 13. The one or more non-transitory computer-readablestorage medium of claim 10, wherein the instructions, when executed,further cause the processor to: receive an indication that the secondsystem has transitioned from the second mode to the first mode; and inresponse to the indication, stream data from the second memory to one orboth of the first memory and the first output device.
 14. A computerimplemented method comprising: determining, by a first system, a mode ofoperation of a second system, wherein the first system comprises firstmemory and a first output device, and wherein the second systemcomprises second memory and a second output device; while the secondsystem is in a first mode, wherein the first mode is a normal operationmode, receiving, by the first system and from the second system, a firstsubset of the first data from the second memory; while the second systemis in the first mode, outputting, by the first system and via the firstoutput device, the first subset of the first data received from thesecond system; while the second system is in the first mode, storing, inthe first memory, a second subset of the first data from the secondmemory; while the second system is in the first mode, synchronizing datastored in at least a part of the first memory with data stored in atleast a part of the second memory via synchronization information,wherein the synchronization information includes a packet identificationnumber, a time stamp, or chronological information; and while the secondsystem is in a second mode, wherein the second mode is a low poweroperation mode, outputting, by the first system and via the first outputdevice, the second subset of the first data from the first memory. 15.The method of claim 14, wherein the second mode is a low power operationmode during which the second system is inaccessible to the first system.16. The method of claim 14, further comprising: receiving, from thesecond system, the first subset of the first data from the second memorybased on the second system executing a first application; andoutputting, via the first output device, the second subset of the firstdata from the first memory based on the second system executing a secondapplication.
 17. The method of claim 14, further comprising: receivingan indication that the second system has transitioned from the secondmode to the first mode; and in response to the indication, streamingdata from the second memory to one or both of the first memory and thefirst output device.
 18. An apparatus comprising means to implement amethod of any of the claims 14-16 and 17.